The present invention relates to a beverage package. More particularly it concerns beverages containing gas, such as carbon dioxide and/or nitrogen, in solution and packaged in a sealed container which, when opened for dispensing or consumption of the beverage, causes gas to be evolved or liberated from the beverage to form, or assist in the formation of, a head of froth on the beverage. The beverage to which the invention relates may be alcoholic or non-alcoholic; primarily the invention was developed for fermented beverages such as ale, lager, stout or other beer and cider but may be applied with advantage to so-called soft drinks and beverages, or drinks such as spirits, liquors, wine and the like.
Beverage packages are known which comprise a sealed container having a chamber containing the beverage with gas in solution and forming a headspace comprising gas at a pressure greater than atmospheric and in which chamber is located initiator means for liberating gas from solution in the beverage so when the package is opened to open primary headspace to atmospheric pressure, such liberated gas developes a froth or foam in the headspace.
A preferred form of initiator means is responsive to a pressure differential that is developed when the headspace is opened to atmospheric pressure for dispensing or consumption of the beverage and the pressure differential causes beverage and/or gas to be injected from a secondary chamber into a main chamber charged with beverage in the container so that such injection causes gas from solution in the beverage to be released and form bubbles which grow rapidly to rise throughout the volume of beverage in the container and develop a head of froth in the headspace of the container. A further known initiator means comprises a material within the chamber of the container having a surface or struture, such as a micro-porous structure, on or within which the beverage reacts to liberate gas from the solution so that when the headspace of the container is opened to atmospheric pressure bubbles of the gas rise from the surface of the aforementioned material throughout the beverage causing liberation of further gas to form a froth in the headspace. This latter form of initiator means has a relatively slow response in comparision with the rapid response effected by the beverage and/or gas injection initiator means and as such the latter initiator means has found greater preference commercially.
For some beverages, particularly those containing carbon dioxide in solution [with or without nitrogen gas in solution] it is possible for a major part, if not all, of the gas in solution to be evolved from the beverage shortly after the package is opened and the initiator means has reacted to liberate gas from the beverage so that the liberated gas seeds a growth of bubbles throughout the beverage to develop the froth. As a consequence, when the beverage is dispensed from the container into a drinking glass for consumption, it is possible that the absence, or low level, of gas in solution in the beverage will impart undesirable characteristics to the beverage [albeit that such beverage may have a good quality head of froth]. This is particularly the case for so-called light beers or lagers where it is preferred that a reasonable volume of gas, usually carbon dioxide, is retained in solution in the beverage as dispensed in a drinking glass so that such gas can evolve naturally to rise as minute bubbles within the beverage and the latter retains a "sparkle" which is considered desirable aesthetically and can add to the consumers enjoyment and "mouthfeel" of the beverage. It is an object of the present invention to provide a beverage package of the kind generally discussed which alleviates the aforementioned disadvantage of excessive liberation of gas in solution so that the beverage when dispensed will retain a desirable "sparkle" without detracting from the desirable characteristics required for froth development in forming a head on the beverage.